The robots in Rengoku aren't your usual Spacely Sprockets robots, so they look more like something from Neon Genesis Evangelion or an H.R. Geiger sketchbook. This could have translated into a really dark, grisly style, but instead it's dull. The environments rarely amount to more than earth-toned boxes, making it easy to get turned around and requiring you to constantly refer to your map, which forces you to pause the game completely to access. The androids don't look much better, with stilted animations and often indistinguishable appearances, thus adding further to the design of repetition that permeates Rengoku. The music tries to carry some of the aesthetic deadweight of the visuals by showing fleeting signs of inspiration with some decent percussion-driven techno and eerie piano tracks. The in-game sound effects, on the other hand, are consistently flat and are often ill-fitting to the actions they accompany.
The promise of character customization could have redeemed much of Rengoku's ill-conceived gameplay. A.D.A.M. doesn't just hold weapons in his hands; they actually become parts of his body, giving him a creepy, Cronenberg vibe. But the actual customization proves too shallow to really tap into same obsessive gamer traits that have made games like Diablo long-standing favorites. There are different weapon and performance upgrades you can pick up from enemies or the occasional crate, but there simply aren't that many different items to find.
When you do find a cool new piece of gear you'd like to use, the game won't let you equip it on the fly. Instead, it forces you to trudge back to the terminal. Aside from making sure your own health bar doesn't deplete entirely, each weapon has an individual energy rating for you to worry about, and it deteriorates with each use of the weapon. Once the weapon energy rating goes down to zero, you're back to bare-knuckle brawling, which forces you to backtrack to the terminal at the beginning of the level to recharge. Basically, however, there's a lot of backtracking in Rengoku. In addition to the single-player mode, Rengoku features a four-way deathmatch mode, as well as a mode where you can trade items with other players...the former of which would be a nice addition if the actual gameplay in Rengoku was much fun, and the latter of which would be worthwhile if there were more items in the game worth trading.
Though A.D.A.M. may be able to redeem himself by climbing the Tower of Purgatory, Rengoku's fate as a well-intentioned dungeon crawler corrupted by poor design decisions is sealed. Even on a platform as new as the PSP, there are better options for those looking for hack-and-slash action, making Rengoku a difficult game to recommend to anyone.